FIELD OF INVENTION
This invention relates to novel 1-carba(1-dethia)-3-cephem-4-carboxylic and 3-cephem-carboxylic acid derivatives which contain unique 3,4-dioxo-1-cyclobutenyl moieties in the C-3 position. The compounds of the instant invention were found to possess potent antibacterial activity. Thus, in another aspect, this invention relates to their antibiotic use and pharmaceutical compositions. Also included within the scope of the present invention are useful intermediates for the synthesis of said antibiotics.